//===- llvm/ADT/SmallVector.cpp - 'Normally small' vectors ----------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file implements the SmallVector class.
//
//===----------------------------------------------------------------------===//

#include "pch.h"
#include "SmallVector.h"
#include <stdexcept>
#include <string>

// Check that no bytes are wasted and everything is well-aligned.
namespace {
struct Struct16B {
	alignas(16) void* X;
};
struct Struct32B {
	alignas(32) void* X;
};
}

static_assert(sizeof(SmallVector<void*, 0>) ==
	sizeof(unsigned) * 2 + sizeof(void*),
	"wasted space in SmallVector size 0");
static_assert(alignof(SmallVector<Struct16B, 0>) >= alignof(Struct16B),
	"wrong alignment for 16-byte aligned T");
static_assert(alignof(SmallVector<Struct32B, 0>) >= alignof(Struct32B),
	"wrong alignment for 32-byte aligned T");
static_assert(sizeof(SmallVector<Struct16B, 0>) >= alignof(Struct16B),
	"missing padding for 16-byte aligned T");
static_assert(sizeof(SmallVector<Struct32B, 0>) >= alignof(Struct32B),
	"missing padding for 32-byte aligned T");
static_assert(sizeof(SmallVector<void*, 1>) ==
	sizeof(unsigned) * 2 + sizeof(void*) * 2,
	"wasted space in SmallVector size 1");

static_assert(sizeof(SmallVector<char, 0>) ==
	sizeof(void*) * 2 + sizeof(void*),
	"1 byte elements have word-sized type for size and capacity");

/// Report that MinSize doesn't fit into this vector's size type. Throws
/// std::length_error or calls report_fatal_error.
[[noreturn]] static void report_size_overflow(size_t MinSize, size_t MaxSize);
static void report_size_overflow(size_t MinSize, size_t MaxSize) {
	std::string Reason = "SmallVector unable to grow. Requested capacity (" +
		std::to_string(MinSize) +
		") is larger than maximum value for size type (" +
		std::to_string(MaxSize) + ")";
	throw std::length_error(Reason);
}

/// Report that this vector is already at maximum capacity. Throws
/// std::length_error or calls report_fatal_error.
[[noreturn]] static void report_at_maximum_capacity(size_t MaxSize);
static void report_at_maximum_capacity(size_t MaxSize) {
	std::string Reason =
		"SmallVector capacity unable to grow. Already at maximum size " +
		std::to_string(MaxSize);
	throw std::length_error(Reason);
}

// Note: Moving this function into the header may cause performance regression.
template <class Size_T>
static size_t getNewCapacity(size_t MinSize, size_t /*TSize*/, size_t OldCapacity) {
	constexpr size_t MaxSize = std::numeric_limits<Size_T>::max();

	// Ensure we can fit the new capacity.
	// This is only going to be applicable when the capacity is 32 bit.
	if (MinSize > MaxSize)
		report_size_overflow(MinSize, MaxSize);

	// Ensure we can meet the guarantee of space for at least one more element.
	// The above check alone will not catch the case where grow is called with a
	// default MinSize of 0, but the current capacity cannot be increased.
	// This is only going to be applicable when the capacity is 32 bit.
	if (OldCapacity == MaxSize)
		report_at_maximum_capacity(MaxSize);

	// In theory 2*capacity can overflow if the capacity is 64 bit, but the
	// original capacity would never be large enough for this to be a problem.
	size_t NewCapacity = 2 * OldCapacity + 1; // Always grow.
	return std::clamp(NewCapacity, MinSize, MaxSize);
}

template <class Size_T>
void* SmallVectorBase<Size_T>::replaceAllocation(void* NewElts, size_t TSize,
	size_t NewCapacity,
	size_t VSize) {
	void* NewEltsReplace = std::malloc(NewCapacity * TSize);
	if (VSize)
		memcpy(NewEltsReplace, NewElts, VSize * TSize);
	free(NewElts);
	return NewEltsReplace;
}

// Note: Moving this function into the header may cause performance regression.
template <class Size_T>
void* SmallVectorBase<Size_T>::mallocForGrow(void* FirstEl, size_t MinSize,
	size_t TSize,
	size_t& NewCapacity) {
	NewCapacity = getNewCapacity<Size_T>(MinSize, TSize, this->capacity());
	// Even if capacity is not 0 now, if the vector was originally created with
	// capacity 0, it's possible for the malloc to return FirstEl.
	void* NewElts = std::malloc(NewCapacity * TSize);
	if (NewElts == FirstEl)
		NewElts = replaceAllocation(NewElts, TSize, NewCapacity);
	return NewElts;
}

// Note: Moving this function into the header may cause performance regression.
template <class Size_T>
void SmallVectorBase<Size_T>::grow_pod(void* FirstEl, size_t MinSize,
	size_t TSize) {
	size_t NewCapacity = getNewCapacity<Size_T>(MinSize, TSize, this->capacity());
	void* NewElts;
	if (BeginX == FirstEl) {
		NewElts = std::malloc(NewCapacity * TSize);
		if (NewElts == FirstEl)
			NewElts = replaceAllocation(NewElts, TSize, NewCapacity);

		// Copy the elements over.  No need to run dtors on PODs.
		std::memcpy(NewElts, this->BeginX, size() * TSize);
	} else {
		// If this wasn't grown from the inline copy, grow the allocated space.
		NewElts = std::realloc(this->BeginX, NewCapacity * TSize);
		if (NewElts == FirstEl)
			NewElts = replaceAllocation(NewElts, TSize, NewCapacity, size());
	}

	this->set_allocation_range(NewElts, NewCapacity);
}

template class SmallVectorBase<uint32_t>;

// Disable the uint64_t instantiation for 32-bit builds.
// Both uint32_t and uint64_t instantiations are needed for 64-bit builds.
// This instantiation will never be used in 32-bit builds, and will cause
// warnings when sizeof(Size_T) > sizeof(size_t).

template class SmallVectorBase<uint64_t>;

// Assertions to ensure this #if stays in sync with SmallVectorSizeType.
static_assert(sizeof(SmallVectorSizeType<char>) == sizeof(uint64_t),
	"Expected SmallVectorBase<uint64_t> variant to be in use.");
